Refractory coating for metal

ABSTRACT

Disclosed is a heat resistant composite comprising a refractory coating on a metal substrate. The refractory coating is provided by mixing a refractory mortar with water, impregnating a water absorbent web of fibrous material with the liquid mixture, placing at least one layer of the impregnated web on a surface of the substrate as a coating, and drying the coating to remove the water and cause the refractory mixture to chemically bond. The substrate may be a pipe protected by the coating for use in injecting a refining agent beneath the surface of a molten metal composition comprising a scrap metal such as copper or aluminum.

FIELD OF THE INVENTION

This invention relates to a refractory coating for extending the usefullife of a metal substrate in the presence of a molten metal composition,and more particularly to a coated metal pipe useful in the refining offerrous and non-ferrous metals. A method and device for manufacturingthe product also is disclosed.

BACKGROUND OF THE INVENTION

In a blast furnace, smelting furnace, reclaiming furnace, or similaroperation for melting and processing metals, a metal pipe is utilized toinject a refining agent beneath the surface of a molten metalcomposition held in a refractory vat or other container to aid in theremoval of impurities from the metal. Previously, the pipe used totransport the refining agent would be consumed rapidly within the vatand need to be replaced on a frequent basis. Disclosed herein is arefractory coating which substantially reduces the rate of consumptionof the metal pipe.

DISCLOSURE OF THE INVENTION

The improved pipe of the invention can perform the function of injectinga reducing or other refining agent beneath the surface of a molten metalbath while lasting many times the life span of the previously useduncoated pipe. It is therefore an object of the present invention isprovide an improved lance for injecting a refining agent directly into amolten metal composition within a melting vat.

A further object of the present invention is to utilize a metal pipe asa core or base structure for an improved refractory coating to provide acomposite pipe or lance for injecting a refining agent into a desiredarea within a melting vat for refining and/or reclaiming a metal.

Another object of the present invention is to provide means for securinga new lance segment to a partially consumed lance segment in order tocontinue the flow of a refining agent to a desired area within a meltingvat. metal pipe which is to be used within a metal melting vat in orderto extend the life span of the pipe.

Another object of the present invention is to use a water absorbent,non-refractory web in order to coat a metal substrate with a refractorycomposition and thereby provide a composite for use in contact with amolten metal composition.

Still another object of the present invention is to immerse an absorbentnon-refractory wrapping material in a liquid refractory mixture in orderto provide a flexible refractory material for wrapping a metal pipe tomake a composite pipe for use in a metal melting vat.

Another object of the present invention is to impregnate and coat aporous flexible web by passing the web around a tension bar immersed ina liquid refractory mixture and then wind the impregnated and coated webonto a pipe base under tension.

Still another object of the present invention is to remove the excess ofa liquid homogenous refractory mixture impregnated into an absorbent webby skimming the excess mixture from the web.

Another object of the present invention is to provide a fast-dryingrefractory wrap which may be trapped and secured around a pipe base toform a refractory coated pipe which is fast-drying.

A further object of the present invention is to provide a compositewhich may be shaped into a desired bent configuration after an absorbentweb impregnated with a liquid refractory mixture has been coated anddried on a substrate of the composite.

A further object of the present invention is to surround a metal pipewith a non-refractory web embedded within a cured and dry refractorycomposition to enable the pipe to be bent into curved shapes withoutfracture or separation of the refractory composition.

Still another object of the present invention is to provide a pipecoated with a dried and chemically reacted refractory composition whichdoes not separate from the pipe or fracture when the coated pipe is bentinto non-linear shapes.

The present invention also provides a method and apparatus formanufacturing the composite pipe. These and other objects and featuresof the invention will be apparent from the following description andappended claims.

According to the present invention, a water absorbent web of porousmaterial is impregnated with a curable liquid refractory mixture. One ormore plies of the impregnated web are applied to a metal substratebefore the refractory mixture sets and while it is still liquid (wet).The composite pipe is then air dried, either at ambient temperature orwith heating, to form a dry refractory coating firmly adhered to thesubstrate. The impregnated web may be used to provide a dry refractorycoating on a wide variety of metal substrates, such as steel plates,bars and pipes. A preferred application is the provision of a dryrefractory coating on carbon steel pipes which are used as lances forinjecting reducing gases and other refining agents beneath the surfaceof a molten mass comprising a metal being refined or otherwise treatedto produce substantially pure metal from a metal ore or from scrapmetal. The refractory coating extends by a substantial amount the usablelife of the metal substrate when in contact with a molten metalcomposition at temperatures in the range of preferably about 1100° F. toabout 3400° F., more preferably about 1400° F. to about 3200° F., andmost preferably about 2000° F. to about 2800° F.

The liquid refractory mixture is preferably a refractory mortar mixedwith water. As used in this specification, "refractory mortars" comprisefinely ground dry refractory material which becomes plastic when mixedwith water, is air or heat settable, and is suitable for use in layingrefractory brick of the type used in making the lining of furnaces suchas those used in refining metals. The preferred refractory mortarsgenerally comprise at least one high temperature (calcined) refractoryaggregate, and at least one raw (naturally occurring) refractory powder,such as the various commercially available clays which may serve as abinder for the aggregate. Additional refractory aggregates and/oradditional refractory powders may be used in various combinations. Wherethe clay used does not provide sufficient cohesiveness, special bindermaterials also may be present. Also, special plasticizing materials maybe present to improve the workability of the liquid mortar composition.

The refractory mortar composition of the present invention preferablycomprises about 50% to about 60% calcined bauxite as a first refractoryaggregate, about 20% to about 30% calcined flint clay or kaolin clay asa second refractory aggregate, about 5% to about 15% raw flint clay orkaolin clay as a refractory powder, and about 5% to about 15% of sodiumsilicate as a binder, all percentages being by weight unless otherwisespecified. Preferably, the mortar further includes about 1% to about2.5%, based on the total weight of the other dry components (usuallyinorganic oxides), of organic starch which serves as a plasticizer toimprove the handling characteristics of the mortar when it is mixed withwater (for example, its workability and body).

The particle size of the refractory aggregates is preferably less thanabout 35 mesh, more preferably in the range of about 65 mesh to about100 mesh. The particle size of the refractory powder is preferably lessthan about 325 mesh and the particle size of the sodium silicate andstarch should be sufficiently fine to dissolve readily in water,preferably less than about 100 mesh, more preferably less than about 200mesh, and most preferably less than about 325 mesh. The bauxitepreferably is of the type found in South America, more preferably in thecountries of Surinam and Guyana. The sodium silicate is preferably of ananhydrous type which dissolves more slowly in water than the hydratedtypes.

Refractory mortars of the type employed in the invention arecommercially available and may be obtained either wet (premixed withwater) or dry. Wet mortars are available from both Babcock & Wilcox ofAugusta, Ga., and the AP Green Company of Mexico, Mo. The dry mortarpreferably contains about 67% alumina, about 27% silica and about 2%sodium oxide relative to the total weight of inorganic oxides.

A preferred refractory mortar is available as a dry mortar mixdesignated Mul-Set F from Babcock & Wilcox, Insulating ProductsDivision, Augusta, Ga. The liquid refractory composition is made up bymixing this dry mortar with water, preferably at a temperature of about160° F. to about 170° F., to provide a composition having a slurry-likeconsistency. The weight ratio of water to mortar is preferably about 10%to about 15%, more preferably about 12% to about 14%, most preferablyabout 13%. This liquid mortar composition is air setting. According toBabcock and Wilcox, the air set composition has a maximum servicetemperature of about 3200° F., and the dry mortar prior to admixturewith water and in the absence of starch has the following chemicalanalysis:

                  TABLE I                                                         ______________________________________                                        Chemical Analysis of dry Mul-Set F:                                           Name           Chemical Symbol                                                                            Percent                                           ______________________________________                                        Alumina        Al.sub.2 O.sub.3                                                                           67.1                                              Silica         SiO.sub.2    27.0                                              Titanium Oxide TiO.sub.2    2.37                                              Ferric Oxide   Fe.sub.2 O.sub.3                                                                           1.20                                              Calcium Oxide  CaO          0.05                                              Magnesium Oxide                                                                              MgO          0.04                                              Sodium Oxide   Na.sub.2 O.sub.3                                                                           2.06                                              Potassium Oxide                                                                              K.sub.2 O    0.19                                              ______________________________________                                    

The web material is made preferably from a porous, non-refractory,organic fiber, preferably a naturally occurring fibrous material, morepreferably a plain-woven fabric of jute or hemp known as burlap. A juteburlap is preferred as being more water absorbent, flexible andstretchable. A preferred burlap is an open weave fabric of tightly andcleanly spun jute threads, a preferred thread size being about 20 toabout 60 mils, more preferably about 30 to about 40 mils. The burlapfabric is preferably relatively light in weight, about 6 to about 8ounces per square foot being preferred and about 7 ounces per squarefoot being most preferred. The burlap is preferably woven so that thefabric has a warp of about 10 to 12 threads per inch and a weft of about8 to 10 threads per inch. A preferred jute burlap is sold as 7 ounceburlap and is available from Harper Crawford Bag Company of Charlotte,N.C. The burlap is sufficiently water absorbent to provide a goodcapillary or "wicking" action which conveys moistures to the edges ofthe web and to the outer surface of the outermost wrap or winding of theweb so as to facilitate rapid drying of the impregnated and wound burlapweb.

The core or base of the coated pipe or lance of the present inventioncomprises a standard metal pipe. Although a wide variety of metal pipesmay be used, the preferred metal pipe is made of relatively inexpensivecarbon steel, such as A-120 carbon steel. While the size of the pipealso may vary over a wide range, the preferred pipe size for metalrefining lances has a nominal diameter of about 1 inch. The thickness ofthe pipe also may vary over a wide range, the diameter and wallthickness of the pipe combining to define the weight of the pipe perunit length. In selecting a pipe wall thickness, the cost of the pipemust be balanced against the effect of increased thickness on its usefullife, pipes of greater wall thickness tending to last somewhat longer ina molten metal bath but also costing more. Thus, while either heavier orlighter pipe may be used in practicing the invention, ASTM Schedule 40pipe is preferred as being the best balance between the cost of thematerial and the rate of consumption of the coated pipe. The weight ofcarbon steel schedule 40 pipe is about 1.68 pounds per linear foot,whereas the weight of carbon steel schedule 80 pipe is about 2.17 poundsper linear foot. Where pipe couplings are used to secure one threadedsegment of coated pipe to the next, the couplings are preferablystandard merchants couplings.

For ease of winding and for use as a lance in metal refining, each pipecore segment is preferably about 101/2 feet long. After beingimpregnated with the liquid refractory composition, the coated burlapweb is wound onto a 101/2 foot pipe segment, preferably using theapparatus and method described below. The coated length is preferablyabout 10 feet 2 inches, leaving about 2 inches at either end forconnection to adjoining pipe segments, about 1.25 inches of each endpreferably being threaded for a coupling. The burlap web preferably isabout 6 inches wide and preferably is wound so that each windingoverlaps the next by about 5 to about 5.25 inches, thereby leaving about3/4 to 1 inch of the previous winding uncovered. This gives a total ofabout 6 to about 8 spiral wraps per 6 inches of pipe length such thatafter the initial 5 to 51/4 inches of wrapped pipe, there are a total of6 to 8 plies of the coated burlap web layered one on top of the other.This requires about 17 yards of the preferred burlap material for eachpipe segment of 101/2 feet. The 6 to 8 plies of coated burlap webincreases the outside diameter of a 1 inch nominal diameter schedule 40pipe from about 1.25 inches to about 2.25 inches. The weight of thiscoated pipe is about 2.75 pounds per linear foot.

Using the apparatus and method of the invention, the wrapping of each10.5 foot segment requires only about 20 to 25 seconds. This method andapparatus also provides sufficiently tight windings that the coatingcomposition is caused to flow or "weep" through the successive layers ofporous burlap so that any excess coating material will flow to theexterior surface of the last wrap of burlap, from which it may beremoved or "skimmed" by hand or mechanical means. After the excessliquid composition is removed from the wrapped pipe, the coated pipe isremoved from the apparatus and put aside to air dry. This drying processmay be speeded up by radiant and/or convection heating, but this may addsignificantly to the cost and is preferably avoided. So as to maintain arelatively uniform drying rate throughout the transverse cross-sectionof the coating and thereby facilitate air drying, each segment of coatedpipe is preferably stood on one end and supported in this verticallyextending position throughout the drying process by a rack or othervertical support, such as a wall.

The rate of air drying of the wrapped coating on the pipe may varygreatly depending on the type of burlap used and the composition of therefractory mortar, particularly the nature of the sodium silicateingredient. Thus, while other refractory mortar compositions may be usedfor the coating and other woven or non-woven burlap webs may be used,drying times with such materials may vary between one and several weeks.A major advantage of the preferred burlap web impregnated with thepreferred refractory composition is that the wrapped pipe coating willdry sufficiently for handling of the composite lance in about 3 days,although drying for one or two more days may be employed to insure thequality of the final product.

The coated pipe of the present invention is used as a lance to inject areducing gas or other treating agent for purifying a metal, preferably anon-ferrous metal, more preferably copper or aluminum. About 3 to 8feet, preferably about 5 feet, of the lance is immersed below thesurface of a bath of the molten metal contained in the vat portion of afurnace so as to inject the reducing agent, preferably an oxygencontaining gas such as air, well below the surface of the molten metalbath.

The coated pipe of the present invention has many advantages over theuse of a bare (uncoated) metal pipe as a lance for introducing reducingor other treating agents below the surface of a molten mass of coppermaintained at a temperature of about 2700 to about 2800° F. in arefining or reclaiming furnace. While a 101/2 foot segment of bareschedule 40 pipe is consumed in about 3 minutes, the coated schedule 40pipe lasts about 45 to 60 minutes. The life of the pipe core is thusextended by a multiple of at least about 10 times, preferably about 15to 16 times, by using the refractory coating of the present invention.

Even with the increased material and labor costs associated with makingthe coated pipe, use of the coated pipe results in an overall savings inmaterial costs of about 2/3 relative to the material costs of using barepipe. In other words, the cost of using the coated pipe is about 1/3 ofthe cost of using bare pipe when considering only the cost of the barepipe material versus the cost of the coated pipe material. The inventionprovides still further cost savings by reducing the labor costsassociated with actually inserting the consumable lances into the moltenmetal bath of a furnace since the number of 101/2 foot segments ofcoated pipe required is substantially less than the number of bare pipesegments otherwise used. These labor costs are also reduced by a factorof 3, that is, the cost of handling the lance of the present inventionat the refinery is about 1/3 of the cost of handling a bare pipe lance.

A further advantage of the present invention results from the use ofsubstantially less (by a factor of as much as 15 or 16) metallic pipe,which is preferably carbon steel. Consumption of carbon steel pipe in afurnace for refining non-ferrous metals introduces iron and othercontaminates into the non-ferrous metal being refined. Thus, use of thepresent invention reduces such contamination by about the same factor,namely, contamination with the present invention is about 1/15th or1/16th of that experienced with bare pipe. Very little additionalcontamination results from the coating material since the burlap isburned and removed as gaseous combustion products, and the refractorycomposition deposits out in the slag as additional refractory materialsimilar to the refractory bricks of the furnace itself.

A still further advantage of the invention is that the coated pipe maybe bent through a significant arc after the coating has set by airdrying. This allows the coated pipe to be bent so as to form a curvedlance that may be inserted in the furnace through a side door instead ofan overhead door. Thus, the coated pipe of the present invention iseasily bent into non-linear shapes and therefore easily adapted for usein furnaces having side entry or offset overhead entry doors. The lancesmay be delivered as straight segments of coated pipe and then bent bythe end user into an appropriate shape without cracking or otherfracture of the refractory coating. It is believed that the burlap webof the preferred embodiments makes the dried coating sufficientlystretchable and flexible to prevent fracture of the coating and/or itsseparation from the metal pipe core.

The metal pipe base provides an elongated tubular core structure with acontinuous opening from the first end of the pipe base to the second endof the pipe base through which the refining agent may travel. Therefining agent is preferably a gas or a pneumatically conveyed solid.The material secured to and surrounding the pipe base is operative toinsulate the pipe base from the molten metal and other heated externalsurroundings in the melting vat when the lance is placed in the meltingvat. A first connecting area on the first end of the pipe base extendsoutward from the refractory material which is secured around the pipebase. A second connecting area on the second end of the pipe baseextends outward from the refractory material which is secured around thepipe base. The first connecting area has a threaded portion and thesecond connecting area has a threaded portion.

The coated web improves the insulating properties of the pipe. Theplasticizer and binder components aid in holding the coated web on thepipe base. The free end of the coated web is preferably secured underthe first one or two windings of the coated web in order to lock thebeginning portion of the spiral windings securely onto the pipe base.Although an uncoated or dry web may first be wound around the pipe baseand then impregnated with the liquid refractory coating composition, itis preferred to first coat the web and then wind the coated web aroundthe pipe base.

A device is disclosed for placing the impregnated web around a pipe baseor other metal core. The device has a trough, pipe securing meanspositioned above the base of the trough, pipe turning means, and webdispensing means. The securing means is operative to rigidly secure thepipe in position for rotation about its longitudinal axis. The turningmeans is connected to the securing means and is operative to turn thesecuring means and the pipe attached thereto. The dispensing means isoperative to dispense the web after it has been secured to the pipe andwhen the turning means turns the pipe to wind the web thereon.

The liquid refractory coating composition is placed within the troughand the web is moved through the trough prior to being placed around thepipe. Bar means is secured within the trough above the base of thetrough and below the normal level of the coating composition. The web ispulled around the bar means in order to move the material through thecoating composition and onto the pipe. Liquid dispensing means islocated outside of the trough and is operative to feed the coatingcomposition to the trough.

Cutting means is operative to cut the web dispensed from the webdispensing means when the coated web has been completely placed aroundthe pipe in the desired number of windings and/or layers. The securingmeans comprises a drive shaft portion which connects to the turningmeans and a coupler portion which connects the drive shaft to the pipeand to which the pipe may be rigidly secured.

The method for placing the web material around a pipe base comprisessecuring a segment of the pipe above the trough, securing the free endof the web material from the web dispensing means to the pipe, andturning the pipe. When the pipe is turned, the web material is pulledfrom the web dispensing means and wrapped around the pipe. The coatingcomposition is placed in the trough and the web material is pulledthrough this composition when the pipe is turned

The method further comprises causing the web material to move around abar means within the trough in order to pull the material beneath thesurface of the coating composition and force the composition into theporous and water absorbent web material when the pipe is turned. Themethod further comprises moving the web dispensing means along thelength of the trough, thereby enabling the web to be wound spirallyaround the length of the pipe segment. The tail end of the web materialfor each pipe segment is cut from the continuous supply of web materialprovided by the web dispensing means after the desired length of web hasbeen placed around the length of the pipe segment. The method furthercomprises removing excess coating composition from the web materialafter the web has been placed around the pipe. The coated pipe is thenremoved from above the trough and placed into preferably a verticalposition to dry.

The refractory composition, upon drying at room temperature, forms achemically-bonded dry refractory coating in which the web material ispermanently embedded. This dry refractory composition, at temperaturessufficiently high to fuse glass and the like, forms a ceramically-bondedrefractory coating from which organic web material has beensubstantially removed by combustion.

The liquid mixed with the dry refractory mortar is preferably potablewater. The specific type and proportions of each component of therefractory mortar may be determined relative to the pH value of themolten metal composition in the melting vat. The coated pipe may beshaped into a desired configuration after the coating mass has been setand cured, without breaking either the pipe base or the coating mass.The pipe may be shaped into the configuration of a non-linear pipe witha radial bend. The angle of the radial bend preferably is in the rangefrom greater than 0° to about 90°.

The process for treating a molten metal composition with the coated pipecomprises providing a supply of a refining or other treating agent, andutilizing the coated pipe to convey the treating agent from this supplyto the desired area of a melting vat containing the molten metalcomposition. Where the furnace surrounding the vat has a side entrance,transport means also may be utilized to support the coated pipe in ahorizontal position. The transport means also helps move the free end ofthe horizontal pipe through the side entrance and to the desired area ofthe melting vat. Where a non-linear pipe with a radial bend is used, asupply end portion is secured to the transport means so as to aid inplacing the free end of the pipe opposite to the supply end into thedesired area of the melting vat.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood more fully from the following detaileddescription and appended claims when taken with the drawings in which:

FIG. 1 is a schematic representation of a coated lance pipe 4 beingutilized within a melting vat 1.

FIG. 2 is a transverse sectional view of lance pipe 4 taken along lines2--2 of FIG. 1.

FIG. 3 is a fragmentary view in partial section of a new lance pipe 26secured to lance pipe 4 of which a major portion has been consumed in amelting vat.

FIG. 4 is a fragmentary perspective view showing a pipe base 11 beingwrapped with a web 29 of coating material which is in loose form and hasa free leading end 20.

FIG. 5 is a fragmentary perspective view similar to FIG. 4 but showingthe web 29 of coating material drawn tightly around the pipe base 11.

FIG. 6 is a schematic representation of an uncoated web 27 of materialbeing removed from a material roll 25 and coated with a liquidrefractory composition 24 to become a web 29 of coating material whichis wrapped around pipe base 11 to form the composite pipe 4 having arefractory coating 10.

FIG. 7 is a top plan view of a pipe coating device 31.

FIG. 8 is a front elevational view of pipe coating device 31.

FIG. 9 is a cross-sectional view of pipe coating device 31 taken alonglines 9--9 of FIG. 7.

FIG. 10 is a fragmentary perspective view of a tucking procedureutilized to lock the free leading end 62 of coated web 51 onto pipe 49.

FIG. 11 is a flow diagram illustrating schematically the composition ofa refractory liquid that can be utilized for the refractory compositionwith which the web is impregnated.

FIG. 12 is an elevational view of a curved lance pipe 69 connected to atreating agent supply pipe 67 by a coupling 68.

FIG. 13 is a schematic representation of curved lance pipe 69 beingutilized in melting vat 1.

FIG. 14 is a schematic representation of curved lance pipe 69 secured toa transport means 72 prior to insertion in melting vat 1.

FIG. 15 is a schematic representation of curved lance pipe 69 secured totransport means 72 and in position within melting vat 1.

FIG. 16 is a schematic representation of curved lance pipe 69 secured totransport means 72 and removed from melting vat 1 after being partiallyconsumed.

FIG. 17 is a perspective view of the transport means 72.

DESCRIPTION OF BEST MODE AND OTHER EMBODIMENTS

Referring now to the drawings in more detail, FIG. 1 is a schematicrepresentation of a treating agent dispensing pipe or lance 4 beingutilized within a melting vat 1. Melting vat 1 could be a vat which isutilized in melting and processing steel or any form of ferrous ornon-ferrous metal composition. Melting vat 1 may be formed by a portionof a metal processing furnace. Melting vat 1 is shown as having amelting electrode 5 connected by wiring 7 to an electrical power source8. Melting electrode 5 may be used to a melt a scrap metal mass 2 withinthe melting vat 1 to form a molten bath 3. Any number of meltingelectrodes 5 may be utilized, only one being shown for purposes ofillustration.

The lance 4 may be placed through an overhead opening 6 in melting vat1, the free end 28 of lance 4 being placed beneath the surface of moltenbath 3 at any desired area within the melting vat 1. Through lance 4flows a treating agent, such as a reducing gas to refine the metal, froma supply 14 of the treating agent. The treating agent flows through aflexible conveying conduit or hose 13 and through a pipe coupling 12into the lance 4.

The lance 4 comprises a pipe base 11 with a coating material 10 securedthereto. Control means 9 moves the lance 4 within the melting vat 1. Thecontrol means 9 may be any pipe movement control means desired,including automatic machinery or manual means.

The supply 14 may supply a reducing gas of pure oxygen or of air oranother mixture containing oxygen. The gas supplied may include aheating fuel such as propane for combustion in the furnace, or any othertreating agent(s) as desired. The control means 9 causes movement of thelance 4 in a manner so that the treating agent is dispersed throughoutthe desired area. The treating agent(s) helps purify the desired metalto be recovered and the combustible fuel supplies heat by combustion toaid in melting scrap metal 2 into molten bath 3.

As shown in FIG. 2, lance 4 has a pipe base 11 and a coated webproviding a coating 10 wrapped around the pipe base 11. The coating 10comprises at least one layer of coated web material 29. A plurality oflayers of coated web material may be wrapped around the pipe base 11 toform a multilayer cover for the pipe base 11. The web material is coatedby impregnating the web with a liquid refractory coating composition.This composition provides sufficient adhesion to laminate the windingsof the first layer to the pipe and successive layers to each other andto hold the coated web material in place on the pipe base until thecomposition sets, which further increases the adhesiveness of the firstlayer to the pipe and successive layers to each other.

The web material can be immersed in the coating composition or thecoating composition can be applied to the dry web in any manner desired,such as by brushing. Various materials may be utilized for the dry webprovided they are porous and water absorbent. The web may be burlap,cotton, wool or some other natural fiber or synthetic fiber havingsubstantial porosity and water absorbance, such as porous fibers madefrom organic polymers. The web material is impregnated with a liquidrefractory mortar of the type previously described.

The ingredients of the refractory composition utilized may be varied inorder to minimize contamination of the metals being melted within themelting vat 1. Considerations for the metals being processed, includingthe pH values thereof, along with other factors, may be utilized informulating the refractory composition for providing the coating 10. Itis preferred that the overall pH of the coating substantially match thepH of the molten metal composition to be processed with the aid of thecoated pipe. The preferred coating composition described above isneutral to slightly basic, use in processing a molten copper compositionof comparable pH.

The coating of the invention extends the life span of the pipe base 11considerably. However, after a period of time, even the coated pipe 4will deteriorate within the melting vat 1. As the end 28 of lance 4deteriorates, more of the lance 4 will be extended into the melting vat1 in order to place the end 28 into the desired area. As thedeterioration approaches a pre-determined length of the lance 4, thelance 4 is removed from the melting vat 1 and the end of base pipe 11connected to pipe coupling 12 is disconnected from this coupling.

Pipe coupling 12 is then connected to one end of a new lance 26 asillustrated in FIG. 3. The other end of new lance 26 is secured to anon-reused pipe coupling 30. The unconsumed section of lance 4 is alsosecured to the non-reused pipe coupling 30. Thereby, when lance 4 isextended back into the melting vat 1, the complete length of this lanceis utilized by being entirely consumed by heat disintegration intomolten bath 3. The non-reused pipe coupling 30 also disintegrates andthe second lance 26 becomes the means for the treating agent to enterthe appropriate area of the melting vat 1 until the eventualdisintegration of the second lance 26. Thereafter, the lance replacementprocess is continuously repeated.

As shown in FIG. 3, the lance 26 has a pipe base 16, and a refractorycoating 15 secured around the pipe base 16. A small portion of the pipebase 16 extends out from the coating 15. This bare end portion hasthreads 19, which are secured within the threads 18 of non-reusedcoupling 30. The pipe base 11 of lance 4 also has a small portionextending out from the coating 10. This bare end portion of pipe base 11has threads 17, which are secured within threads 18 of non-reused pipecoupling 30. The lance 4 is rigidly secured to the lance 26 by thenon-reused pipe coupling 30.

One desirable method of wrapping either the dry or coated web is to tuckthe leading free end 20 of the web 29 under the first winding of web 29so as to form a locking relationship between the free end, the firstwinding and the pipe base at the beginning of the spiral wrapping inorder to firmly secure the leading end portion of the web to the pipebase 11. The end 20 is carried around the pipe and placed underneath thefirst wrapping and is then wrapped over by one or more loose windings asshown in FIG. 4. The first layer of coated web material 29 is then drawntightly around the pipe base 11 in order to secure the web so that itcan be wound onto the pipe base 11 without requiring a separatefastener. This tuck locking arrangement is sufficiently secure to pullthe web from a dispensing means and through a web coating device. InFIG. 5, the end 20 of web 29 is shown tucked tightly under the firstwrapped layer of the coated web material in order to firmly secure thestill wet coating onto the pipe base 11.

FIGS. 4 and 5 illustrate the beginning stages of wrapping a continuousweb 29 of coated material around the pipe base 11 in accordance with apreferred method. In practice, the layers of coated web material may beapplied to the pipe base 11 or any other substrate in any desiredmanner, and the web material may be of any desired shape and size. Theweb material may be applied to the substrate either before or afterimpregnation with the refractory composition. Continuous web 29 may bewrapped onto pipe base 11 so that successive windings are spaced anydistance apart desired and successive layers are overlaid to anymultiple layer thickness desired.

FIG. 6 is a schematic representation of an uncoated web 27 of fibrousmaterial being removed from a supply roll 25 and coated with arefractory composition 24 to become a coated web 29, which is thenwrapped around pipe base 11 to form the coated lance 4. The web 27 ofuncoated material is shown entering over roller 21 into an impregnatingvat 23 containing the coating composition 24. The web 29 of coatedmaterial is shown exiting over a second roller 22 and being wrappedaround the pipe base 11 in order to form the coating 10 of compositelance 4. The uncoated web 27 of material can be immersed in the coatingcomposition 24 or the coating composition can be applied to the uncoatedweb 27 without immersion, such as by passing the web between a pair ofcoating rollers or by brush or roller coating one side of the web at atime.

FIG. 7 is a top view of a pipe coating device 31. Pipe coating device 31has a liquid holding trough 32. Liquid holding trough 32 has a backpanel 33, a side panel 34, an opposing side panel 35, and a bottom panel36. Utilized with trough 32 are a pipe turning means 42, a web fabricdispensing means 44, and a liquid coating dispensing means 43. Toutilize the pipe coating device 31, a pipe segment 49 is secured bythreads at one end to a threaded coupling 63. Coupling 63 is secured toa pipe drive shaft 53 which extends through a bearing flange 54. Pipedrive shaft 53 is connected to pipe turning means 42. The other end ofpipe segment 49 is placed into an end bearing flange 64. The end bearingflange 64 and the drive shaft bearing flange 54 allow the drive shaft53, the coupling 63, and the pipe 49 to be rotatably mounted over thetrough 32 so that the entire length of pipe 49 may be turned by pipeturning means 42. Bearing flange 54 may provide one or more annularbearing surfaces on the inside and outside of the side panel 34 throughwhich the pipe drive shaft 53 may extend and turn within.

Web dispensing means 44 may be movably mounted on a web dispensing bar41. Web dispensing bar 41 is supported by bar end supports 37 and 38,support 37 having a slot 39 and support 38 having a slot 40 forreceiving the ends of bar 41. If this configuration is utilized, the webdispensing bar 41 may be lifted from bar supports 37 and 38 and a newweb dispensing means 44 can be added to replace the old web dispensingmeans 44, when all of the fabric or other web material is dispensed fromthe old web dispensing means 44.

The fabric web extends into the trough 32 and around a tension bar 52.Tension bar 52 can turn and is rotatably mounted at each end in annularbar bearing flanges 65 and 66. Bearing flange 65 is within side panel 34of trough 32 and bearing flange 66 is within side panel 35 of trough 32.These bearing flanges frictionally engage the ends of bar 52 so that itwill cause tension in the web. The dispensing means 43 dispenses theliquid coating composition 48 into the trough 32 so that the dry web 50from web dispensing means 44 will pass through the liquid coatingcomposition 48 while passing around tension bar 52. The composition 48impregnates and adheres to the fabric or other wrapping material of dryweb 50 to provide a coated web 51. The coated web 51 is wound onto pipe49 when the pipe turning means 42 is activated to turn the drive shaft53 which is rigidly secured to pipe 49. The turning of pipe 49 pulls thecoated fabric 51 and winds it around pipe 49. While being pulled andwrapped, coated fabric 51 is tensioned by tension bar 52 and by beingpulled over and around the outer front edge of bottom panel 36 of trough32 as shown in FIG. 9. Fabric dispensing means 44 is moved along fabricbar 41 at a rate which determines the winding angle at which coated web51 is placed onto pipe 49. This in turn establishes the number of spiralwindings per unit of pipe length and thereby the number of layers ofcoated web forming the pipe coating.

When the coated web material 51 has covered the desired length of thebare pipe 49, a cutting means 45 may be used to cut the wound portion ofthe web from the continuous portion of the web supplied by dispensingmeans 44. The tail end of the cut fabric is then wrapped onto the pipe49 as the last windings. The cutting means may comprise blades 46 and 47which cooperate to cut the coated web 51.

Any excess liquid 48 on the pipe 49 may then be removed. This liquidpreferably has a slurry-like consistency and is easily removed by handor by a mechanical skimming means. The excess composition is preferablyremoved while the pipe 49 is over trough 32 so that the excesscomposition will drop back into trough 32 to be re-utilized. The coatedpipe 49 is then uncoupled from the coupling 63 and removed from pipecoating device 31 in order for the coating to set and dry. The driedcoated pipe may then be utilized as previously described.

The pipe turning means 42 may be any type of conventional pipe turningdevice from a simple manual pipe turning mechanism to any type of motordriven pipe turning apparatus desired. The pipe turning means 42 may besimply a motorized rotational means, such as a drill. The fabricdispensing means may be motorized and/or automated or simply a roll offabric rotatably and slidably mounted on bar 41 so as to be unwound andmoved along an axis parallel to the pipe as the pipe 49 is rotated. Thedispensing means 44 may include not only means to dispense the fabricfrom a roll, but means to move the fabric roll along the dispensing bar41. The human worker 60 may actually control movement of the roll with aportion of his body, such as his leg or knee.

The mortar dispensing means 43 may be any type of automated liquid orpaste dispensing system or may be a very simple manual dispensing means,such as a person pouring mixed mortar into the holding trough 32. Thecutting means 45 may be any type of cutting means from an automatedcutting mechanism to the manual act of cutting the fabric web from aroll of web material with shears.

Trough 32 may be of any shape or size desired. The bottom panel 36 andthe back panel 33 may be placed at any desired angle to form an angledrear to hold the liquid mortar composition 48 in the area where the web50 passes around tension bar 52 and becomes impregnated with composition48 to become coated wrapping material or coated web 51. The pipe coatingdevice 31 has four support legs, 55, 56, 57, and a fourth leg not shownin the drawings, which support the trough 32. The bottom panel 36 of thetrough 32 has a drain valve 58 in order to drain and clean the bottompanel 36 and the interior of trough 32. The pipe coating device 31 maybe placed on any supporting surface, such as floor 59.

The web tucking and locking procedure utilized in the method and devicefor manufacturing the coated pipe is illustrated in FIG. 10. A humanworker 60 with hands 61 may physically tuck the leading edge 62 ofcoated web 51 under the oncoming continuous web to form a tight tucklock at the beginning of the wrapped coating. In this tuck lock, theleading end of the web is brought over the top of bare pipe 49, woundcompletely around it, and placed back up under the portion of web 51which will form the next wrap and is coming forth from around thetension bar 52 after being coated with the refractory composition. Whenthe leading edge 62 of the coated web is tucked under the oncomingcoated web 51, turning means 42 is activated to rotate pipe 49 and pullthe overlying wrap(s) tightly around the pipe, which jams the leadingend portion 20 between the pipe surface and the overlying wrap(s) tosecurely lock the leading end portion of the web to the bare pipe 49 asshown in FIG. 5. By tuck locking the coated web 51 to the pipe 49 andthen rotating the pipe with frictional drag to tension the web, frictionand pressure are generated which securely lock the leading end 20 of theweb between the pipe and the overlying wrap(s) of web 51. This tuck lockmethod provides a secure attachment of the beginning wraps of coated web51 to the bare metal of pipe 49 and thereby eliminates the need forextraneous fasteners.

When pipe 49 with the web secured thereto is turned by the pipe turningmeans 42, more of the coated web 51 is pulled onto and wrapped aroundthe pipe 49. As the fabric dispensing means 44 is moved along the fabricdispensing bar 41, the coated material 51 moves along the tension bar 52and is wrapped around the pipe 49 in consecutive spirals which areoverlapped or otherwise spaced relative to each other dependent on thespeed of translational movement of dispensing means 44 relative to thespeed of rotation of pipe 49.

The coated web 51 is preferably cut by the cutting means so that severalinches of bare pipe before the end of pipe 49 are not covered with thecoated web 51. The operator preferably manually wraps the lead and tailportions of the cut coated web 51 around the pipe 49 so as to leave atleast about two inches of bare pipe exposed at each end. If themid-portion of pipe 49 is only partially covered with coated web 51 whenthe dry web 50 runs out, the fabric dispensing means 44 can be replacedand the process begun again anywhere along the partially coated pipe 49desired.

FIG. 11 is a flow diagram illustrating the chemical ingredients of arefractory composition that can be utilized for coating composition 24or 48. As shown in FIG. 11, a refractory mixture 92 is produced from acombination of refractory powder 87, high temperature (calcined)refractory aggregate 88, binder 89, plasticizer 90, and liquid 91.According to this invention, the speed at which the refractory mixture92 sets can be changed in several ways. A different binder might beadded or a different web material might be used to carry the liquidrefractory composition. The relative proportions of the ingredients alsomay be varied for the same purpose.

The refractory mixture 92, when dried at room temperature 93, willchemically bond due to the nature of the ingredients of the refractorymixture. When the chemically-bonded composition 94 is subjected to afusing temperature 95, a ceramically-bonded composition 96 results. Thisceramically-bonded composition 96 has ceramic bonds which provide anamorphous glass-like phase which holds the aggregate(s) together.Crystalline phases of ceramic compounds also may be present afterfusion. The high temperature refractory aggregate 88 may simply becalcined kaolin, which is a refractory aggregate, or may be acombination of calcined refractory aggregates. One or more rawrefractory aggregates may be ground or otherwise pulverized to providerefractory powder 87. Alternatively, a naturally fine raw clay ormixture of raw clays may be used alone or combined with a pulverizedaggregate powder to provide refractory powder 87.

Refractory powder 87 and binder 89 provide strength and refractoryproperties to the coating 10 or 15 at high temperatures. The binder 89,basically, provides the strength of the mortar on air setting at ambienttemperature. The plasticizer 90 helps provide a viscosity andconsistency which enables the liquid refractory mixture 92 to be appliedto dry web 50. The plasticizer 90 may or may not have refractoryqualities, and is preferably a non-refractory organic material such asstarch. The liquid 91 is preferably potable water.

The refractory mixture 92 may have a high or low viscosity, dependingupon the amount of liquid 91 utilized. A relatively low viscosity ispreferred. The amount of liquid 91 added to the dry refractory mortar ispreferably an amount sufficient to make a smooth homogenous liquid ofslurry-like consistency, namely, a soupy liquid having a viscositysubstantially less than self-supporting paste and substantially greaterthan water alone (similar to milk of magnesia). A method and device forapplying the refractory mixture 92 to the pipe 11 or 49 have beenpreviously described with reference to compositions 24 and 48.

FIG. 12 is an elevational view of curved lance pipe 69 connected to anextension pipe 67 by a coupling 68. Curved lance pipe 69 has anappropriate radius of curvature 73, such as about thirty-six (36")inches or greater. The radius dimension 73 may be any desired radiuswhich, in essence, would give a desired curve to lance pipe 69 withoutfracturing the dry refractory coating.

FIG. 13 is a schematic representation of curved lance pipe 69 beingutilized in melting vat 100 having a side entry opening 71 normallycovered by a door plate 70. In FIG. 1, a lance pipe 4 is shown beingutilized in the melting or processing vat 1 having an overhead entrydoor. Any desired plurality of lance pipes 4 or 69 may be utilized atthe same time through the same or different furnace doors.

It is desirable that the treating agent be placed directly into themolten solution 3. If a treating agent is added through a side dooropening 71, the lance utilized may aim the treating agent and/or acombustible fuel above the molten metal solution 3 until such time asthe pipe bends from the intense heat so that the curved end may then bedropped into the molten solution 3 to inject the treating agent belowthe surface of the molten solution. Instead of such heat bending whichis relatively slow and is difficult to accomplish consistently andaccurately, pipe 69 may be bent mechanically by any desired pipe bendingapparatus after the refractory mixture 92 has set and cured at roomtemperature to form a chemically-bonded composition 94 on the pipe core49. Such mechanical bending is along an arc preferably having a radiusof at least 36 inches to avoid fracturing the coating.

FIG. 14 is a schematic representation of curved lance pipe 69 secured toa transport means 72 prior to insertion in melting vat 100. Transportmeans 72 is movable along floor 97 outside of melting vat 100. When acurved lance pipe 69 is secured through a coupling 68 to an extension orsupply pipe 67, pipe 67 may be held at an appropriate level by thetransport means 72. The treating agent flows from supply source 14,through flexible transporting conduit or tube 13, through extension pipe67, which may be positioned by control means 9, through the curved lancepipe 69, and into the molten solution 3 through door opening 71.

FIG. 15 is a schematic representation of curved lance pipe 69 secured totransport means 72 and in position within melting vat 100. Door plate 70has been moved to uncover opening 71. Transport means 72 has been movedtoward melting vat 100 to place lance pipe 69 through the door opening71 and to place the free end of curved lance pipe 69 into the moltensolution 3. Treating agent may now be transported from its source 14,through the lance 69, and into the molten solution 3.

FIG. 16 is a schematic representation of lance 69 on transport means 72after being partially consumed and removed from melting vat 100. After aperiod of time, even the coated pipe 69 of the present invention will beconsumed by the molten solution 3. When a pre-determined portion oflance 69 is consumed, transport means 72 may be moved back from themelting vat 100, removing the remainder of curved lance 69 from themelting vat 100 through door opening 71. The unconsumed remainder oflance 69 may be removed from coupling 68 by pipe removal means, such asa large wrench, and a new curved lance pipe may be secured thereto inorder to resume the process of adding further treating agent to themolten solution 3, as desired.

FIG. 17 is a perspective view of transport means 72. Means 72 may bereplaced by any other desired transport means. Transport means 72 has apipe base tray 74 to hold extension pipe 67. Pipe base tray 74 issupported on floor 97 by support legs 76, 77 and 78. A pipe hold-downchain 75 may be placed over pipe 67 to secure this pipe and lance 69 totransport means 72. Support leg 77 has a caster base 80, support leg 78has a caster base 79, and support leg 76 has a base plate 81. Supportleg 76 may be raised in order to roll transport means 72 on caster bases79 and 80 and thereby move transport means 72 toward and away frommelting vat 100. The depth that the treating agent is placed into themolten solution 3 can be controlled by utilizing a predetermined radialbend in the curved lance pipe 69.

While the invention has been described with reference to specificembodiments, the description is illustrative and is not intended to beconstrued as limiting the scope of the invention. Various modificationsand changes may occur to those skilled in the art without departing fromthe spirit and scope of the invention as defined by the followingclaims.

What is claimed is:
 1. A heat resistant composite comprising arefractory coating adhered to a metal substrate, said composite beingprovided by:mixing a dry refractory mortar with water to provide aliquid refractory mixture; impregnating a water absorbent web of fibrousmaterial with said mixture; coating a surface of said substrate byplacing at least one layer of said impregnated web on said surface as acoating; and, drying said coating to remove said water from said web andsaid liquid refractory mixture and to cause said liquid refractorymixture to set and dry as a chemically bonded refractory compositionadhered to said metal substrate and having said web embedded therein,said dry refractory mortar being suitable for laying refractory brick inthe lining of metal refining furnaces and for causing said liquidrefractory mixture when dried to form said chemically bonded refractorycomposition at ambient temperature and a ceramically bonded refractorycomposition at a fusing temperature above said ambient temperature. 2.The composite of claim 1 wherein said substrate is carbon steel.
 3. Thecomposite of claim 1 wherein said substrate is a metal pipe and saidcoated surface is on the exterior of said pipe.
 4. The composite ofclaim 3 wherein said pipe is made of carbon steel.
 5. The composite ofclaim 4 wherein said pipe surface is coated with a plurality of layersof said impregnated web.
 6. The composite of claim 1 wherein saidsurface is coated with plurality of layers of said impregnated web. 7.The composite of claim 1 wherein said fibrous material comprises aporous organic material.
 8. The composite of claim 1 wherein saidfibrous material comprises burlap.
 9. The composite of claim 8 whereinsaid burlap comprises jute.
 10. The composite of claim 8 wherein saidburlap is in the form of a woven fabric.
 11. The composite of claim 10in which said fabric has a warp with about 10 to 12 threads per inch anda weft with about 8 to 10 threads per inch.
 12. The composite of claim11 wherein said threads have a diameter of about 20 to about 60 mils.13. The composite of claim 1 wherein said drying is provided by air atambient conditions and said refractory coating is substantially drywithin five days of commencement of said drying.
 14. The composite ofclaim 1 wherein said refractory mortar comprises a calcined refractoryaggregate having a particle size greater than about 65 mesh, arefractory powder having a particle size less than about 325 mesh, abinder, and a plasticizer.
 15. The composite of claim 14 wherein saidrefractory aggregate is at least one of calcined flint clay, calcinedkaolin clay and bauxite; wherein said refractory powder is at least oneof flint clay and kaolin clay; wherein said binder is sodium silicate;and wherein said plasticizer is starch.
 16. The composite of claim 15wherein said refractory mortar comprises about 50% to about 60% calcinedbauxite, about 20% to about 30% calcined kaolin clay, about 5% to about15% raw kaolin clay, about 5% to about 15% sodium silicate, and about 1%to about 2.5% starch, the percentages of bauxite, clay and silicatebeing relative weight percentages excluding starch and the percentage ofstarch being a weight percentage relative to the total weight of saidother ingredients.
 17. The composite of claim 14 wherein a chemicalanalysis of said dry refractory mortar comprises about 67% alumina,about 27% silica and about 2% sodium oxide relative to the total weightof inorganic oxides.
 18. The composite of claim 17 in which said dryrefractory mortar further comprises about 1% to about 2.5% starchrelative to the total weight of inorganic oxides.
 19. The composite ofclaim 16 wherein said silicate is anhydrous, and wherein said bauxite isSouth American bauxite such as from the countries of Surinam or Guyana.20. The composite of claim 14 wherein said water is mixed with saidrefractory mortar in a weight ratio of about 0.12 to about 0.14.
 21. Thecomposite of claim 14 wherein said refractory composition issubsequently heated to a temperature sufficient to cause ceramic bondingthereof.
 22. The composite of claim 21 in which said refractorycomposition becomes ceramically bonded at a temperature in the range of1500° F. to 2000° F.
 23. The composite of claim 1 which is bendableafter air drying at ambient conditions through an arc of 90° having aradius of about 36 inches without fracture of said coating or separationof said coating from said substrate.
 24. A heat resistant compositecomprising a refractory coating adhered to a metal pipe, said compositebeing provided by:mixing a dry refractory mortar with water to provide aliquid refractory mixture; impregnating a water absorbent web of fibrousmaterial with said mixture; coating at least a portion of the exteriorsurface of said pipe by placing at least one layer of said impregnatedweb on said surface portion; drying said coating to remove said waterfrom said web and said liquid refractory mixture and to cause saidliquid refractory mixture to set and dry as a chemically bondedrefractory composition adhered to said surface portion of the metal pipeand having said web embedded therein; said metal pipe being made of acarbon steel, said fibrous web being made of burlap, and said dryrefractory mortar being suitable for use in laying refractory brick inthe lining of metal refining furnaces and for causing said liquidrefractory mixture when dried to form said chemically bonded refractorycomposition at ambient temperature and a ceramically bonded refractorycomposition at a fusing temperature above said ambient temperature. 25.The composite of claim 24 in which said fusing temperature is sufficientto cause combustion of said burlap.
 26. The composite of claim 1 inwhich said web is made of a non-refractory material, and said fusingtemperature is sufficient to cause combustion of said non-refractoryweb.
 27. The composite of claim 26 in which said fusing temperature isin the range of 1,500° F. to 2,000° F.
 28. The composite of claim 1 inwhich said dry refractory mortar contains sufficient silica to providean amorphous-glass phase in said ceramically bonded refractorycomposition.
 29. The composite of claim 1 in which said substratecomprises a metal pipe, and said refractory coating is adhered to theexterior of said metal pipe to form a composite pipe, said compositepipe being consumable at a rate at least about one-tenth of the rate ofconsumption of said metal pipe when immersed in a molten metalcomposition having a temperature in the range of 2000° F. to 3200° F.30. The composite of claim 1 in which said dry refractory mortarcomprises less than about 20% by weight of calcium oxide.
 31. Thecomposite of claim 30 in which said dry refractory mortar does notcontain more than about 0.05 weight percent calcium oxide.
 32. Thecomposite of claim 1 in which said refractory coating has a maximumservice temperature of about 3,200° F.
 33. A heat resistant compositepipe comprising:a metal pipe; and, a chemically bonded refractorycoating adhered to at least a portion of the exterior surface of saidpipe and having embedded therein a web of water absorbent,non-refractory material such that said composite pipe is bendable atambient conditions through an arc of 90° having a radius of at leastabout 36 inches without fracture of said refractory coating orseparation of said refractory coating from said pipe; said chemicallybonded refractory coating having been formed by wrapping said exteriorsurface portion with a length of said web impregnated with a liquidrefractory mixture made by mixing with water a dry refracory mortarsuitable for laying refractory brick in the lining of metal refiningfurnaces, and drying said wrapping to remove said water from said weband said liquid refractory mixture and to cause said liquid refractorymixture to set and dry as said chemically bonded refractory coating, thecomposition of said dry refractory mortar being such that said liquidrefractory mixture when dried forms said chemically bonded refractorycomposition at ambient temperature and a ceramically bonded refractorycomposition at a fusing temperature above said ambient temperature.